A voltage-tunable amorphous p–i–n thin-film light emitting diodes (TFLEDs) with SiO2-isolation on n+-type crystalline silicon (c-Si) has been proposed and fabricated successfully. The structure of the device with i-a-SiC:H and i-a-SiN:H luminescent layers is indium–tin–oxide (ITO)/p+-a-Si:H/p+-a-SiC:H/i-a-SiC:H/i-a-SiN:H/n+-a-SiCGe: H/n+-a-SiC:H/n+-c-Si/Al. This device revealed a brightness of 695 cd/m2 at an injection current density of 300 mA/cm2. Its EL (electroluminescence) peak wavelength exhibited blue-shift from 655 to 565 nm with applied forward-bias (V) increasing from 15 to 19 V, but the EL peak wavelength was red-shifted from 565 to 670 nm with further increase of V from 19 to 23 V. By comparing with the EL spectra from p–i–n TFLEDs with i-a-SiC:H or i-a-SiN:H luminescent layer only, the EL spectrum of this TFLED could consist of three bands of radiations from the tail-to-tail-state recombinations in (1) i-a-SiC:H layer, (2) i-a-SiN:H layer, and (3) i-a-SiC:H/p+-a-SiC:H junction.
